In recent years, cured products of silicone resin compositions have been proposed for use as encapsulating materials for semiconductor light-emitting elements. However, the cured products of silicone resin compositions tend to exhibit high gas permeability and low barrier properties relative to hydrogen sulfide gas in the air. As a result, when encapsulating is performed using a cured product of a silicone resin composition, a problem arises in that the silver film that functions as the rear reflector of the encapsulated semiconductor light-emitting element may be corroded by hydrogen sulfide in the air, causing a deterioration in the brightness of the semiconductor light-emitting element.
A curable silicone resin composition containing a silicone resin having a refractive index following curing of 1.50 to 1.55 and a silicon oxide filler having an average particle size of 1 to 10 μm that is dispersed uniformly in the silicone resin at a concentration of 1 to 30% by mass has been proposed as a silicone resin composition capable of addressing the above problem (see Patent Document 1).